In ColdFusion, lists and arrays start at index 1, not 0. That's why you can't do listDeleteAt( myList, 0 )
. You can test to see if the list has elements with something like:
<cfif listLen( myList ) gt 0>
(do list delete here)
But otherwise, are you possibly not creating the list before that listDeleteAt() runs? Sounds like this might be the case. Post the relevant code in whichever files that would relate to your problem, and I'll take a look. What you provided is not enough to understand what's going on.